For many video camera applications, e.g. monitoring applications, it is advantageous to use a camera which can pan, tilt (and optionally zoom and/or rotate) to cover a large area. Such a camera is known under the name PT (pan-tilt) camera, PTZ (pan-tilt-zoom) camera etc. During e.g. a pan/tilt motion of the camera, the bit rate of a video stream captured by the camera can reach high levels since most or all pixel blocks within an image frame are encoded using costly I-blocks during such motion, leading to an increased bit rate. Alternatively, the encoding quality of the video stream is reduced during such motion of the camera to decrease the bit rate. However, this may result in a generally blurred out video stream.
Within image processing there is a continuing effort put into reducing bit rate or image size while maintaining a perceived quality of an image. A solution to the above problem is to adapt a motion vector search range of the encoder encoding the video stream according to the speed of the pan/tilt adjustment. Since searching for matching blocks of pixels between two images usually requires a large amount of arithmetic computation and an increased motion vector search range lead to that more comparisons is made, a problem with this solution is that the computational complexity of the encoding process will increase, thus requiring more processor power and/or increased processing time for completing the encoding process.
There is thus a need for improvements within this context.